1. Field of the Invention
The present invention relates to an adhesive composition and an endoscope device.
2. Description of the Related Art
It is necessary for an endoscope to make a diameter of a part inserted into a body cavity (insertion part) as narrow as possible for inserting it into the body cavity, or the like. Various items are incorporated inside the insertion part to diversify the functions of the endoscope.
For example, various tubes are incorporated into the insertion part of the endoscope, and an adhesive is used for fixing open parts of the tubes to the tip or an operation part. In addition, an optical system is provided on a hard part of the tip of the insertion part for observing the inside of a body cavity. The optical system includes a cover lens and lenses thereof, and a cover lens and lenses thereof for illumination from a light guide, and an adhesive is used for fixing these lenses on a lens frame or the hard part of the tip.
Within the insertion part are further incorporated a light guide for transmitting light to the tip part, and an image guide for transmitting an image to an eyepiece part. Fiber bundles, in which a number of fibers are bundled, are used for the light guide and the image guide. An adhesive is used for fixing the fiber bundles to the lens frame or the hard part of the tip part.
As regards an electronic endoscope, in addition to the tubes and fiber bundles described above, cables, which transmit electric signals to a connector part from a CCD and the like within the hard part of the tip part, are also incorporated. An adhesive is used for protecting and fixing the CCD and the like.
The adhesive is also used for finishing an outer surface of the endoscope. Prior to the finishing using the adhesive, an edge of a flexible sheath tube is tightly bound with threads from the outside, which is fixed on a member inside thereof. In order to secure an insertion property of the flexible sheath tube and prevent loose threads, an adhesive is coated on the threads. In this way, the finishing of the outer surface and the fixing of the threads are performed.
The endoscope is required to be completely sterilized, because it is inserted into the body cavity of a patient. The endoscope is subjected to a sterilization treatment using an autoclave with high temperature and high pressure steam, or a sterilization treatment using a chemical such as peracetic acid or gas (such as hydrogen peroxide gas or ethylene oxide gas). When a medical device such as an endoscope is subjected to the sterilization treatment using the autoclave or the chemical, the adhesive layer can be deteriorated by saturated steam or the chemical, and thus members bonded by the adhesive may be peeled off from each other.
JP No. 3806635 proposes that deterioration of an adhesive layer is prevented by incorporating predetermined filler in the adhesive to enhance a sterilization resistance even after a sterilization treatment. JP 2002-238834-A discloses that in order to maintain air tightness and durability of a bonded part of lenses and a frame in a bonded lens unit even after a sterilization treatment, the lenses are bonded to the frame using an adhesive containing a thermosetting resin such as an epoxy resin, and a filler. JP No. 4875790 discloses that when certain silica is contained as a filler, an adhesive layer which has sufficient durability against various disinfection methods and which hardly transmits steam can be obtained.